机翼尺度效应对等离子体分离流动控制特性的影响
EXPERIMENTAL INVESTIGATION OF THE INFLUENCE OF SCALING EFFECTS OF WINGS ON THE FLOW SEPARATION CONTROL USING PLASMA ACTUATORS
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摘要: 等离子体流动控制技术是一种以等离子体气动激励为控制手段的主动流动控制技术. 为了进一步提高等离子体激励器可控机翼尺度, 以超临界机翼SC(2)-0714大迎角分离流为研究对象, 以对称布局介质阻挡放电等离子体为控制方式, 以测力、粒子图像测速仪为研究手段, 从等离子体激励器特性研究出发, 深入开展了机翼尺度效应对等离子体控制的影响研究, 提出了适用于分离流控制的能效比系数, 探索了分离流等离子体控制机理, 掌握了机翼尺度对分离流控制的影响规律. 结果表明: (1)随着机翼尺度的增大, 布置到机翼上的激励器电极长度会相应增加; 在本文的参数研究范围内, 激励器的平均消耗功率不会随电极长度的增加而线性增大; 当电极长度达到一定阈值时, 激励器的平均消耗功率趋于定值; (2)在固定雷诺数的情况下, 随着机翼尺度的增大, 等离子体的控制效果并未降低, 激励器能效比系数提高; (3)等离子体在主流区诱导的大尺度展向涡与在壁面附近产生的一系列拟序结构成为分离流控制的关键. 研究结果为实现真实飞机的等离子体分离流控制, 推动等离子体流动控制技术工程化应用提供了技术支撑.Abstract: Plasma flow control technology is an active flow control technology with plasma aerodynamic actuation as the control means. In order to further improve the controllable wing scales of plasma actuator, experimental investigations on characteristics of symmetrical dielectric barrier discharge (DBD) plasma actuator and flow separation control over a supercritical wing SC(2) - 0714 at high angle of attack using symmetrical DBD plasma actuator have been carried out by the force measurement and particle image velocimetry (PIV). The influence of wing scaling effect on plasma control is deeply studied and the energy consumption ratio coefficient suitable for separated flow control is proposed. In addition, the separated flow control mechanism of the plasma actuator is explored, and the influence law of Wing scale on separated flow control is mastered. The results show thats (1) with the increase of wing size, the length of copper foil electrode arranged on the wing is increased accordingly. The average power consumption of the actuator does not increase linearly with the increase of the electrode length within the scope of parameters in the present manuscript. When the electrode length reaches a certain threshold, the average power consumption of the actuator tends to a fixed value. (2) In the case of fixed Reynolds number, with the increase of wing scale, the control effect of plasma is not decreased, and the energy consumption ratio coefficient of plasma actuator increases. (3) The large-scale spanwise vortices and a series of coherent structures which are generated by the symmetrical DBD plasma actuator in the mainstream flow area and in the vicinity of the wall respectively become the key to the control of separated flow. The research results provide technical support for realizing the separated flow control of real aircraft using plasma actuators and promoting the engineering application of plasma flow control technology.